There is known a molecular sieve carbon (hereinafter referred to as MSC), for example, as an adsorbent for separating air into oxygen and nitrogen. This MSC is produced using a carbonized charcoal prepared by carbonization of, for example, a carbon material such as cokes, coal and coconut shell char or of thermosetting resins such as phenol resins. It should be noted here that carbonization treatment is to subject a cured thermosetting resin to dry distillation to volatilize components other than carbon.
FIG. 1 shows an example of prior art process for producing an MSC using a thermosetting resin.
A starting material thermosetting resin 1 is cured in a curing step S1 to obtain a cured resin 2, which is then subjected to dry distillation in a dry distillation step S2 to obtain a dry distillate 3. Subsequently, the dry distillate 3 is pulverized in a pulverizing step S3 over an ordinary pulverizer such as a ball mill to provide a pulverized product (primary particles) 4, and the pulverized product 4 is admixed with a binder to be granulated in a granulating step S4 to obtain a granule 5. The granule 5 is further subjected to carbonization in a carbonizing step S5 to provide a carbonized charcoal 6. The carbonized charcoal 6 is then subjected to heat treatment in a heat treatment step S6 and then to pore size adjustment and the like in a pore adjustment step S7 to carry out adjustment of pore opening and the like to give an MSC 7.
Incidentally, it is possible to subject the cured resin 2 directly to the pulverizing treatment in the pulverizing step S3 without undergoing the dry distillation step S2.
Meanwhile, when a commercially available cured thermosetting resin powder 8 is employed as the raw material, the carbonized charcoal 6 can be obtained by subjecting the powder 8 directly to the granulating step S4 and then to carbonization in the carbonizing step S5 without undergoing the pulverizing step S3, since the raw material thermosetting resin already assumes a powder form. However, when a finely divided powder is to be formed, the pulverizing step S3 should not be omitted preferably, and, in this case, the powder 8 is subjected. to dry distillation in the dry distillation step S2 to be converted into a distillate 3 which is then subjected to the pulverizing step S3.
In the process for producing an MSC as described above, the pulverizing step S3 is a significant step which determines the particle size and particle size distribution of the carbonized charcoal powder (primary particles) and influences much the performance of the MSC finally obtained.
However, in the conventional process employing an ordinary pulverizer such as a ball mill, although particles of 100 .mu.m or less can be obtained in a short time (about one hour) at the initial stage of pulverization, the particle size cannot be further reduced easily and the particle size distribution is widened even if pulverization is continued for an extended time. Accordingly, the performance of the resulting MSC becomes poor, inconveniently.